AircraftOwner Online

FAQ#1 - I have customers come to my booth at Sun-n-Fun and Oshkosh and complain to me that their 406ELT battery from brand X only lasted 18 to 24 months before replacement was required.  How can this be when it was advertised as a five year battery? 
 

Answer - SARSAT requires the ELT’s to transmit on 406Mhz frequency for a minimum of 24hours on 406Mhz and 48 hours on 121.5Mhz.  If the battery doesn't have enough power to meet this minimum requirement it is considered depleted.

In fact some manufacturers shut down the 406 transmitter after 24 hours of crash activation just to make sure the 121.5 transmitter can make it to 48 hours.  This "meets" certification but you can see how fragile it is.

The owners’ problems come into affect when performing self tests.  Every test draws energy from the ELT battery and an internal counter gives the owner a “failed” indication after the predetermined number of tests. This is to ensure that the ELT can still meet the specifications during an accident. Perform too many tests and the ELT battery fails well before it’s time and if the owner/operator loses track of the number of tests performed or simply didn’t know of this short fall, they fall victim and have to change their battery prematurely.

How do you avoid buying products with these shortfalls?

Ask some questions that will reveal the battery potential:

Does your product require aircraft power for the remote switch?

Does your product need batteries in the remote switch?

How long does the 406Mhz transmitter run in an emergency?

All of these symptoms tell you that the ELT battery cannot handle the load by itself and needs assistance.  This costs you more money in mulitple replacement batteries.
Is there a product out there that does not have this weakness?  Absolutely yes.
If you want a 406ELT that won't break the bank and will give you years of service without hidden weaknesses. Check out the Kannad AF Compact.